To test and compare durability of engine block walls in engines, several solutions have appeared. One example is to use the principle of the so called Hydro Pulse Testing of engine blocks. This is accomplished by pressurizing the cylinders with hydraulic oil. High pressure hydraulic oil is squeezed into the cylinder at a frequency of up to about 15 Hz. The principle of Hydro Pulse Testing is that dummy internal components are used in order to apply a pulsating force onto the engine block walls. This pulsating force simulates the most significant forces on the engine block structure during operating conditions. A number of tests are subjected to pulsating fatigue at different loads until breakage or until a predetermined number of pulsating cycles has run out. The test results are plotted in a pressure/life diagram. By using a well known mathematical method, e.g. a Wöhler diagram, a curve is fitted to the test results. Thus a pressure/life curve describes the fatigue behavior of the tested material or component under constant amplitude. However, there are some problems with the Hydro Pulse Testing method. The very high oil pressure that is required increases the risks of considerable damage to equipment in case of leakage. It is also hard to obtain the high oil pressures needed today and if the trend of raising cylinder pressure in production engines during combustion continues, it will be even harder in the future. The maximum frequency of testing is comparatively low. The method is very time consuming, a test series of seven blocks which is required for making a reliable pressure/life curve, takes about 4 weeks to run.
JP11316174 shows a test method and a testing device of an engine block bearing part, wherein the durability test of a engine block bearing part is executed by fixing a support member for supporting a shaft arranged in the bearing part to be tested by a vibration exciting plate. Even if this method solves the problem with high oil pressure mentioned above, it has some disadvantages.
In the Hydro Pulse Testing case and in the method in JP11316174 the regions around two bolt holes are stressed simultaneously. This means that when one of them breaks, the other is useless for durability evaluation. At most there are only three test results per block. In a series of approximately 20 test results which is common when making a reliably load/life curve, seven engine blocks are required. The consequence thereof is that the Hydro Pulse Testing case and the case described in JP11316174 have the problem that the engine block consumption is very high. An engine block is very expensive and requires a high energy consumption to produce, and a high consumption of them therefore makes these test methods very expensive.